1. Field of the Invention
The present invention relates to an ostomy appliance comprising a deodorising filter, in particular ostomy bags, and to a filter device.
In connection with surgery for a number of diseases in the gastrointestinal tract a consequence is, in many cases, that the patient is left with a stoma such as a colostomy, an ileostomy or an urostomy in the abdominal wall for the discharge of the effluents or waste products of the body, which are conveyed through the colon, the ileum or the ureter. The discharge of visceral contents including intestinal gases cannot be regulated at will, and for that purpose the opening may be closed with a closure means, e.g. a tampon or a magnetic closure, or the patient will have to rely on an appliance to collect the material emerging from such opening in the form of a receiving bag which is later emptied and/or discarded at suitable times.
Ostomy appliances are well known. Such appliances may be two-piece or one-piece appliances. In both types of appliances, an adhesive wafer is attached to the wearer's skin. In case of a one-piece appliance, a receiving member or bag is attached to the adhesive wafer. In case of a two-piece appliance, the adhesive wafer forms part of a body side member and a receiving bag is attached releasably to the body side ostomy member for receiving exudates from the stoma.
When using one-piece appliances, the whole appliance, including the adhesive skin barrier securing the appliance to the skin is normally removed and replaced by afresh appliance. When using two-piece appliances, the body side member is left in place up to several days, and only the receiving bag attached to the body side member is replaced.
The discharge of flatus, measured in volume, may exceed the discharge of solid and liquid faecal matter by many hundred percent and therefore there is usually the need for the continuous or frequent venting of the intestine or the collecting bag. Normally the outflowing flatus is deodorised with a suitable filter. Commonly the active filter is powdered active carbon, which absorbs H2S being the principal component of the smell of flatus.
2. Description of the Related Art
Various constructions of filters for ostomy appliances are known. In the state of the art, the filters are designed so as to obtain a high security of deodorisation of the flatus by securing that there is no by-pass by which the flatus may circumvent the filter, and some measures have been discussed with respect to obtaining a better security against blocking of the inlet of the filter by solid discharged visceral content. When the inlet opening of the filter is blocked, the gas discharged into the ostomy appliance cause ballooning of the bag which is highly undesirable for several reasons. Ballooning will be embarrassing for the user as the bag will bulge and there is an increased risk of leakage which is unacceptable for the user.
European Patent No. 0 235 928 discloses that a filter may be rendered suitable for use with ileostomy equipment when the filter wall adapted to face the source of intestinal gas is covered by a layer of sheet material, preferably plastic sheet material connected to the filter walls and inside the periphery of this connection, provided with openings for the passage of intestinal gas. Conveniently these openings, which may for instance be slits of a width of 0.5-1 mm and a length of a few millimeters, may be situated outside the peripheral edge of the filter body. However, such slits may open if the pressure is high giving free flow of gas and liquid through the layer of sheet material. In the alternative, it is proposed to provide the filter housing on the surface adapted to face the source of intestinal gas with a layer of liquid-absorbing material. The area of the absorbent material is conveniently the same as the area of the filter body or somewhat larger but the positioning on the wall in question should be such that the absorbent material does not cover the inlet opening for intestinal gas to be deodorised since saturation of the liquid-absorbing material with liquid might prevent the passage of the intestinal gas. Furthermore, it is proposed to render the filter particularly efficient for ileostomy equipment by providing it both with a covering sheet and an absorbent layer of material.
EP patent No. 0 443 728 B1 discloses a bag for receiving discharge from the human body comprising a filter and an intervening membrane covering the inlet opening of the filter, said intervening membrane being gas permeable but not liquid permeable. It is mentioned that the membrane may comprise a polyester film bonded to a PTFE film and that such membrane showed no leakage of water. There is no indication of security against leaking when exposed for discharge from an ileostomy or liquids from a colostomy.
U.S. Pat. No. 5,342,434 discloses a gas permeable coated porous membrane having enhanced oleophobic and hydrophobic properties. The membrane may be a PTFE membrane coated with a diisocyanate coating and the membranes are stated to be useful in waterproof, breathable fabrics and gas vents or filters that protect electronic equipment used in or near automotive engines. Although other useful applications are stated to be medical devices where venting filters are needed, this reference is silent with respect to safety against wetting of filters for ostomy appliances by the visceral contents of an ostomy collection bag which contents has a very complex composition of biologically active compounds from the digestive system.
U.S. Pat. No. 4,387,712 discloses a surgical collection bag having two opposed walls secured together by a perimeter weld, said bag having a vent and said bag also having welds inside the bag defining together with the perimeter weld a pathway through which gases can flow from the interior of the bag to the vent. The pathway includes one or more vents through which gases must pass before reaching the vent.
Published International Patent Application WO 98/44880 discloses a filter for covering a vent of an ostomy appliance, said filter comprising an elongated, substantially flat filter body of a porous filter material interposed between gas and liquid impervious walls which are sealed to the body along its longitudinal side edges; gas inlet and outlet openings being provided in communication with the filter material adjacent to its respective longitudinal end regions, wherein both of the gas and liquid impervious walls are sealed to the upper and lower surfaces of the filter body, wherein the inlet opening is covered by a hydrophobic sheet, wherein the inlet opening is covered with a microporous oleophobic membrane and wherein a foam material is covering the inlet opening of the vent. It is disclosed that there may a compartment functioning as an inlet pathway, which pathway may have one or more openings for letting in gas from the interior of the ostomy appliance. Such arrangement shows improved resistance against wetting and blocking of the filter caused by humidity or other liquid constituents of the visceral contents of an ostomy collection bag and, at the same time, shows improved resistance against clogging of the filter.
However, it has been found that, especially for ostomates having an ileostomy and especially at night when they turn in bed, there is a risk of directly pressing faeces in the receiving bag against the inlet opening(s) of the filter and that the pressure may be sufficiently high to force the front of visceral material through a foam material covering a single inlet opening of the vent and past the inlet opening of the filter to cause a blocking of a microporous oleophobic membrane covering the inlet opening of the vent as the one or all of the passage way(s) communicate with one and the same compartment. This applies to both U.S. Pat. No. 4,387,712 and Published International Patent Application WO 98/44880 which both discloses only one inlet opening to the filter.
Thus, there is still a need of measures for effectively preventing blocking of the inlet opening of filters of ostomy appliances.
It has now been found that it is possible to reduce the risk of blocking of the inlet opening of filters of ostomy appliances in a manner that almost eliminates the risk and, at the same time, is simple to carry out in industrial practice.
Thus, it has been found that the above drawbacks can be avoided by improving the form of the passage to the inlet opening of the filter.